Method and apparatus for folding and locking a box blank



Sept. 10, 1968 A. a. RANDLES i 3,400,640

METHOD AND APPARATUSFOR FOLDING AND LOCKING A BOX BLANK Filed July 13,1966 4 sheets sheet 1 & 0m 20 l I Jli g L 10- L l a II I l I I a a-. l8l8 26 'l v 5 L! i INVENTOR.

2 ARTHUR E. RANDLES ,JR.

ATTORNEYS Sept. 10, 1968 A. E. RANDLES METHOD AND APPARATUS FOR FOLDINGAND LOCKING A BOX BLANK 4 Sheets-Sheet 2 Filed July 13, 1966 INVENTOR.ARTHUR E. RANDLES,JR.

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ATTOR NEYS Sept. 10, 1968 A. E. RANDLES 3,400,640

METHOD AND APPARATUS FOR FOLDING AND LOCKING A BOX BLANK Filed July 13,1966 4 Sheets-Sheet 5 I INVENTOR. "5 5 ARTHUR s. RANDLES JR.

ATTORNEYS Sept. 10, 1968 A. E. RANDLES ETHOD AND APPARATUS FOR FOLDINGAND LOCKING A BOX BLANK 4 Sheets-Sheet 4- Filed July 13, 1966 INVENTOR.ARTHUR E RANQLES,JR.

ATTORNEYS 3,400,640 METHOD AND APPARATUS FOR FOLDING AND LOCKING A BOXBLANK Arthur E. Randles, 707 Warrington, Redwood City, Calif. 94063Filed July 13, 1966, Ser. No. 569,003 8 Claims. (Cl. 93-51) ABSTRACT OFTHE DISCLOSURE A device and method for folding and locking the cornersof a box blank of paperboard or the like without glue or separatefastening means by interlocking male and female members integrallyformed in the box panels.

One type of paperboard box in wide use today comprises a main or bottompanel and end and side panels with interlocking members. Theinterlocking members comprise a locking tab extending from the side edgeof one wall panel which is slit diagonally inward from the outer edge toform an upstanding locking tip which enters into a slit formed in theadjacent edge of the other wall panel. The slit formed in the other wallpanel is of generally C-shaped configuration forming a tongue which isdisposed towards the locking tab. Thus, when engaged, the locking tabenters into the slit to underlie the tongue and overlie the adjacentwall panel but with the locking tip underlying the wall panel.

Such corner structure provides a positive lock that has proved veryeffective. Heretofore, however, assembly of the corner required that thelocking tab be inserted under the tongue and that a separate machineelement be applied to pull the tip of the locking tab through to theinside of the complementary wall panel. This requires a rather complexfolding device that is rather expensive to build and less thancompletely reliable in operation.

It is, therefore, an object of this invention to provide a simple butreliable machine for folding and locking the corners of a box blank ofthe type described.

It is a further object of this invention to provide a machine forfolding and locking a box blank of the type described employing aminimum number of movable parts.

It is a still further object of this invention to provide a device forfolding and locking box corners of the type described by application ofsimple mechanisms.

In carrying out this invention, I provide a die with a generallyrectangular opening comprising side and end rails with positioning meansfor locating a box blank with side and end panels thereof supported onthe side and end rails. In cooperative association with the die is aplunger having a generally rectangular base with side and end walls oftrapezoidal configuration inclining inward from maximum width from thebase. The end walls of the plunger are relieved at their ends to formrearwardly inclined anvil surfaces, and protrusions adjacent the anvilsurfaces are inclined forwardly. The plunger moves between the blanksupporting rails to engage the main panel and force the carton throughthe die. During the first portion of the movement of the plunger throughthe die, a stationary cam surface thereon biases the box blank endpanels upward toward the end walls of the plunger while plow-likemembers at each corner engage the locking tabs to fold them into uprightposition. Then, during a subsequent portion of the plunger travel, twopairs of spring pressed fingers engage the side edges of the end panelsto press them firmly against the depressed anvil surfaces, bending themrearwardly while the protrusions on the plunger end walls engage thetongues to bend them forwardly out of the plane of the end panels. Thisopens the United States Patent Office 3,400,640- Patented Sept. 10, 1968slit to a maximum degree to provide free entry for the interlocking tab.In addition, the rearward bending of the end wall side edges, in effect,shortens the distance to the edges so that the side walls can swingbeyond without engaging them and the locking tabs can swing through agreater are below the upper edge of the C-slit to enter it across theoutwardly buckled end panel.

As the plunger continues downward, the plow-like members fold thelocking tabs inward to a plane intermediate that of the free end of thetongue and the rearwardly bent side edges of the end panels so that,upon further travel of the plunger, a second pair of spring pressedfingers folds the side panels upward at their edges to force the lockingtabs into the slits, this movement being permitted by rearwardlyinclined cam surfaces on the edges of the first pairs of spring loadedfingers which permit the locking tabs to pass under them.

During subsequent travel of the plunger the end walls pass out fromunder the first pair of spring pressed fingers, releasing the end panelswhile the second pair of fingers continue to press against the sideedges of the side panels. By pressing against the edges, the side panelsare buckled outward so that the locking tabs will penetrate even furtherinto the C-slit. Then, when the box passes out from under the secondspring loaded fingers, the panels snap back to generally planarconfiguration with the locking tip engaging the inner surface of theside panel. During the final stage of plunger travel, spring pressedstripper fingers pass over the upper edges of the side and end panels toprevent return of the folded box with the plunger.

Other objects and advantages of this invention will become apparent fromthe description following when read in conjunction with the accompanyingdrawings wherein:

FIGURE 1 is a plan View of a box carton blank to be folded in accordancewith this invention;

FIGURE 2 is a view in perspective of the folded box;

FIGURE 3 is a view in perspective of the principal components of a boxfolding device comprising a feature of this invention;

FIGURE 4 is a partial plan view of the folding device and partiallyfolded box blank;

FIGURE 5 is a front view partially cut away of the folding devices asshown in FIGURE 4;

FIGURE 6 is a partial section view taken along line 66 of FIGURE 4;

FIGURE 7 is a partial plan view showing a subsequent stage of operation;

FIGURE 8 is a partial section view taken along line 88 of FIGURE 7; and

FIGURE 9 is a partial section view taken along line 9-9 of FIGURE 7.

Referring more particularly to FIGURES 1 and 2, the box 10 with whichthis invention is used comprises a main or bottom panel 12 with endwalls 14 and side panels 16. Extending from the side edges of the sidepanels are locking tabs 18 which are slit at 20 diagonally inward fromthe tab outer edges to form locking tips 22. When the box is assembledas shown in FIGURE 2, the corners are positively locked with the lockingtab 18 overlying the end panels 14 and underlying tongues-24 formed inthe end panels by generally C-shaped slits 26 with the locking tips 22extending above the slits 26 to engage the inner surfaces of the endpanel 14 and provide a firm interlock.

Referring now specifically to my invention, the box folding and lockingdevice comprises two principal components, a plunger 30 and a die 32.The die 32 comprises side and end rails 34 and 36 on which the side andend panels 14 and 1-6 are supported, being positively located by siderestraining angles 38 and stop member 40 which engages the edge of theleading end panel 14 as it is delivered onto the die in the direction ofthe arrow F in FIGURE 3 by any suitable means (not shown).

The plunger 30 is adapted to be moved down and through the die byconventional reciprocal drive means (not shown) and comprises agenerally rectangular base 42 with trapezoidal side and end walls 44 and46. The trapezoidal configuration of the side and end walls causes themto be inclined inwardly from their maximum widths at their base 42 for apurpose hereinafter to be described.

The side walls 44 of the plunger are generally planar but the end walls46 are relieved adjacent their outer edges to provide rearwardlydivergent anvil surfaces 48. A small bracket 50 secured to each end wallas by means of screws 52 has outwardly extending ears 54 which divergeforwardly from the end wall 46 and are adapted to engage and bendoutward the tongues 24 of an end panel 14 which is pressed against theplunger end wall 46.

As the plunger moves downward in the direction of the arrow P, therectangular base 42 engages the main panel 12 to force the box blankthrough the die 32. During additional movement of the plunger 30 throughthe die 32, folding of the box blank is commenced by forcing the endpanels 14 against and past stationary cam surfaces 56 on the end rails36 to fold the end panels 14 toward upright position, i.e., toward theend walls 46 of the plunger. In the next stage of the plunger travel,the side edges of the end walls are engaged by pairs of spring pressedfingers 58 pivoted at 59 which press on depending supports 36a for thedie 32. The end panel folding fingers are firmly biased against the sideedges of the end panels to press them against the relieved end anvilsurfaces 48 of the plunger 30, the force being exerted by means of aspring 60 against an adjustable stop 6011. As the side edges are bentrearwardly to the position shown in FIGURE 4 which illustrates theright-hand leading corner of the die 32 viewed in the direction of thearrow F in FIGURE 3, the protruding fixed ears 54 on the plunger engagethe tongues 24 in the end panels to bend them forwardly out of the planeof the end panels whereby the slits 26 are fully opened to receive thelocking tabs 18. As shown in FIGURE 6, the leading faces 58a of thespring loaded fingers 58 are rounded and inclined rearwardly at theirouter edges in order to permit the upper edge of the locking tab 18 tocam under it toward engagement behind the extended tongue 24.

As the end panels are folded, downward movement of the plunger 30 forcesthe locking tabs 18 against plowlike fingers 61 which extend diagonallyinward and downward from the corners of the dies so that as the lockingtabs move d wnward along their surfaces they are pushed inward to aplane intermediate that of the end panel side edges 14a and theforwardly bent tongues 24 as shown in FIGURE 4.

After folding of the locking tabs 18 has commenced, the side panels 16engage inclined surfaces 62 on plates 64 which depend from the siderails 34 to commence upward folding of the side panels 16 as shown inFIGURE 5. The depending plates 64, in addition to functioning asstationary cam members, provide a pivotal mounting at 66 for side panelbiasing fingers 68 which are spring loaded at 69 against an adjustablestop device 70.

Referring now to FIGURES 7 and 8, there is illustrated a subsequentstage of operation wherein the side panel forming fingers 68 are bendingthe corner edges 16a of the side panels inward through more than 90actually to deform the corner of the box and to further insert thelocking tip 18. The end panel forming fingers have at this point lostengagement with the end panels, but the end panels are still buckledoutward by pressure of the inner surfaces of the side panels 16 againsttheir end panel edges (FIGURE 7). It will be noted that the side panelforming fingers 68 are inclined at 68:: so that they can force the sidepanel edges beyond the plane of the plunger de wall 44.

Finally, during subsequent travel of the plunger, the side edges moveout from under the forming fingers and enable the side and end panels tospring back toward planar disposition under their natural flexuralstrength, leaving the locking tip 22 firmly interlocked behind the endpanel 14. Then, as the plunger reaches the end ofits stroke, the foldedbox passes beneath stripping fingers 71 (FIGURES 3 and 9) which arepivotally mounted at 72 from depending bars 74. The stripping fingersare spring biased to pass over the top edges of the carton so that whenthe plunger starts its return stroke the box is stripped from theplunger 30 and off the protruding fingers 54 thereon to drop onto adelivery platform (not shown).

Now reviewing the operation of the plunger 30 and die 32 to fold the box10, the plunger forces the box blank between the side and end rails 34and 36. First theend panels 14 are folded upward by engagement of thestationary cam bars 56 and then are folded past and buckled upward bymeans of the spring loaded fingers 58 pressing the ends of the panelsagainst the relieved anvil surfaces 48. This also causes the protrudingfingers to fold the tongues 24 outward. In the meantime, the cornerplows 61 fold the locking tabs 18 into upright planes intermediate thetongues and the end panel edges.

Then the side panels are folded upward, first by the inclined camsurfaces 62 and then by engagement with the side spring loaded fingers68 which force the side corners past 90 against the rearwardly inclinedside wall of the plunger to insert the locking tabs 18 fully.Thereafter, the panels are released and they spring back to planarconfiguration with the corners interlocked.

While this invention has been described in conjunction with a preferredembodiment thereof, it is to be understood that modifications andchanges therein may be made by those skilled in the art withoutdeparting from the spirit and scope of this invention as defined by theclaims appended hereto.

Having described my invention, I claim:

1. A device for folding and locking corners of a 'box blank comprising amain panel, adjacent wall panels hingedly connected to said main panel,a slit in a first one of said wall panels with portions thereof disposedat an angle to each other forming a tongue directed toward the side edgeof said first wall panel, a lock flap hingedly connected to the secondof said wall panels along a side edge thereof, a bendable locking tip onsaid lock flap, said lock fiap underlying said tongue while overlyingsaid first panel and said locking tip underlying said first panel whensaid corners are locked, said folding and locking device comprising:

a plunger having a generally rectangular base and generally uprightwalls forming external corners,

one of said upright walls being relieved at an end thereof to form adepressed anvil surface diverging rearwardly from portions thereofdisplaced from said one end,

a protrusion on said one upright wall diverging forwardly therefrom andengageable with the tongue on a first panel when the side edge thereofis biased against said anvil surface to bend said tongue away from saidone upright wall,

a die including first and second rails forming internal corners throughwhich said external corners are movable,

gauge means on said die for positioning a box blank thereon with saidfirst and second wall panels located respectively on said first andsecond rails,

first biasing means on said die engageable by the first panel of a boxblank during the initial portion of the plunger travel through saidinternal corners to fold said first panel toward said one end wall,

second biasing means on said die engageable by said first panel adjacentthe side edge thereof during a secondary portion of the plunger travelto urge said first panel side edge rearward against said anvil surfacewith said tongue bent forward,

third biasing means engageable by the lock flap of said box blank tofold said lock flap into a plane intermediate said side edge and thefree end of said tongue, and

fourth biasing means engageable by the side edge of the second panel ofsaid box blank during a subsequent portion of the plunger travel to foldsaid second panel into upright position with the locking tip underlyingsaid first panel.

2. The box folding device defined by claim 1 wherein:

said first biasing means releases said first panel side edge during anext subsequent portion of the movement of said plunger while saidfourth biasing means continues to engage said second panel.

3. The box folding device defined by claim 1 including:

spring pressed stripper means movable behind the upper edge of one ofsaid panels at the end of the plunger travel to prevent return movementthereof with said plunger.

4. The box folding device defined by claim 1 wherein said second biasingmeans comprises:

a finger pivotally mounted on said die to pivot in a plane transverse tosaid anvil surface, and

resilient means biasing said finger toward said anvil surface.

5. The box folding device defined by claim 4 including:

a cam surface on said finger inclined from a second panel biasingsurface rearward toward said second rail so that said lock tab may passunder said finger during operation of said fourth biasing means.

6. The box folding device defined by claim 4 wherein:

the side and end walls of said plunger are inclined inward from saidbase so that panels biased against them are folded in excess of 90.

7. The box folding device defined by claim 1 wherein said fourth biasingmeans comprises:

a second finger pivotally mounted on said die to swing in a planetransverse to said second upright wall, and

resilient means biasing said second finger toward said second uprightwall,

the panel-engaging surface of said second finger being inclinedrearwardly from its point of engagement with the side of a second panel,

said second finger being conditioned to swing a distance sufficient tocarry said point of engagement beyond said second upright wall.

8. A method of folding and locking corners of a box blank comprising amain panel, adjacent wall panels hingedly connected to said main panel,a slit in a first one of said wall panels with portions thereof disposedat an angle to each other forming a tongue directed toward the side edgeof said first wall panel, a lock flap hingedly connected to the secondof said wall panels along a side edge thereof, a bendable locking tip onsaid lock flap, said lock flap underlying said tongue while overlyingsaid second panel and said locking tip underlying said second panel whensaid corners are locked, said folding and locking method comprising thesteps of:

bending a first panel of a box blank into upright position,

bending the side edge of said first panel rearwardly and bending saidtongue forwardly, to open said slit and to foreshorten said first panel,

folding the lock fiap of said carton into a plane wherein the lockingtip is intermediate said side edge and the free end of said tongue,folding the second panel into upright position with the locking tipunderlying the tongue on said first panel, pushing the side edge of thesecond panel beyond 90 so that said locking tip extends through the slitand is interior of said first panel, and releasing said first and secondpanels.

References Cited UNITED STATES PATENTS 2,580,180 12/1951 Meller.2,711,677 6/1955 Stenger. 2,896,518 7/1959 Gibb 93-51 3,168,018 2/1965Dunn 9351 3,342,114 9/1967 Dunn 93-S1 WILLIAM W. DYER, JR., PrimaryExaminer.

WAYNE A. MORSE, JR., Assistant Examiner.

